Dynamic clutch torque recorder



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1 mm wa 1 H i A H r O C T A U Law D \m DYNAMI June 11!, 19460 4 Sheets-Sheet 2 June 11, 1946- 1.. u. cAHlLL. ETAL DYNAMIC CLUTCH TORQUE RECORDER Filed April 12, 1944 June L. D. cm-uu. ET AL DYNAMIC CLUTCH TORQUE RECORDER Filed April 12, 1944 4 Sheets-Sheet '5 N 0 0 w mfl rm $5 VCNF Y m M p R H m EPE T L R W R A J Y B .V: 3

L. D. CAHILL ET AL 2,401,907

ORQUE RECORDER June 11, 1946.

DYNAMIC CLUTCH T Filed April 12, 1944 4 Sheets-Sheet 4 flTTOIENE Y curve. In practice,- however, clutches often exthr nes n will a e r h like nne ion with hlbit an undesirable tendency to chatter, or vian external lever t on the head of the starter. bratewith rapid fluctuations occurringin the 40 The particular means for extending the jaw a value 0! torque. When such a condition obtains is likewise aterial to the invention. conventional devices which indicate average Starters having the above described features torque values are obviously inadequate to preare now in common use and the present invention Patented June 11, 1946 2,401,907 DYNAMIC CLUTCH TORQUE RECQEDEIR Ra /sic D. Cahill, Shaker Heights, Joseph J. Neill. South Euclid, and Forrest A. Frampton, Gar tield Heights, Ohio, assiznors, by mesne assign merits. to Jack & Helntz Precision Industries, Inc. @leveland, Ohio, a corporation of Delaware Application dprll 12, 1944, Serial No. 530,600

(Cl. tit 'iltl This invention relates to a device for recording and torque transmitting mechanisms, but for purclutch torque characteristics and has particular poses of illustrating the principles oi the invenapplication to aircraft starters and the like. The tion, the prefered embodiment herein shown and object oi the invention is to provide a treuuency described relates to starters for aircrait engines responsive dynamic clutch torque recorder which 6 and the like.

will make a complete and accurate record of In the drawings:

instantaneous torque values plotted against time. Figure 1 is a view ot a preferred embodiment Aircraft starters for large airplane engines of the invention in side elevation;

exert a cranking torque through the sudden re=-- Figure? la a. top plan view with certain parts lease of energy stored in a rapidly revclvins fly- 10 shown in section;

wheel contained within the starter. In starting Figure 3 is an end elevation view with parts an aircratt ensine the flywheel is first energized broken away;

by an electric motor or hand crank mechanism Figure 4 is a fragmentary side elevation with to impart a high rotational speed thereto. when the casing shown in section, looking from the side the desired rotational speed has been obtained. w opposite that shown in Figure l;

a law on the starter is extended into positive on Figure 5 is a fragmentary top plan view showgagement with a co-mating Jaw on the engine ms t sta ter clamps in locked p s n; and

to be started so that the two are immediately Fi e 6 i a partial v i r to Fi ure 5 positively locked together. A multiple disc clutch showing one or the clamps released. is ordinarily provided in the starter reduction Referring now to the drawings, the numeral i gearing to allow a certain amount of slippage designates an aircraft starter containing an elec until the engine has been accelerated to cranm tric motor, inertia flyw l, r u n rin ins speed, and the device of the present inven= multiple disc clutch. and extensible jaw. These tion is designed to test the operation or uch a, various components are housed within the starter clutch in what is termed locked Jaw periormance, cosine, only the law 2 appearing in the drawings. That is to ay that th flywheel i th start r The particular starter illustrated may he ener is energized to its normal cranking speed and gized alternatively by the above mentioned electhen the starter jaw is extended into engagement tri m t or by a hand crank mechanism conwith a mating law which is positively restrained nectible by fiexible'shait or other means to a hand against rotation, to simulate the conditions en- 80 crank connection 8, the particular means tor en countered in attempting to crank a stlfl or ersizi the starter flywheel being immaterial to firemen engine. the present invention. The starter i may be pro- An ideal clutch in slipping under load would vided with either solenoid or manual means for transmit a substantially steady, non fluctuating extendi the jaw 2, the present starter being protorque until the flywheel energy was nearly (115- 35 vided with both means. The solenoid means for slpated, whereupon the torque, it plotted against extending the Jaw is contained within the starter time, would gradually tail to zero in a smooth housing and the manual means is operable aentatrue picture or performanc F nst is incorporated in the device indicated by the w averag value be atlsfactnry i h 5 numeral d which is designed as a test stand on instantaneous values may vary Irorc. practically which. conventional starters may be readily zero to twice average value, producing a vioraciped and unclamped for testing. The devicetion condition which may be highly objectionable. 5 is n a n wit and upp t d up n a base Itisthereiorethe object 0! the present invention portion 3 having base flange l which may be to provide a testing device sumclently sensitive so securely halted to a test bench or other firm supand responsive to instantaneous values to indl port. The base portion 6 carries a head 8 adaptcate the amplitude and frequency of such vihra= ed to receive and support the starter I in. the tions in the manner of an oscillogram. same manner in which it is intended to he sup- It is to be understood. o1 course that the in ported by its mounting flange on an aircraft enventlonmay be used to test other sot clutches B sine mounting pad. Thus. as shown in Figure 2,

the starter mounting flange 9 is adapted to be clamped against the head 8 by meansof a pair of easily manipulatable clamping arms l0, dowels ll being provided on the head 8 to be received through the usual holes in the mounting flange.

Secured on the rear side of the base] by means of bolts I4 is a resilient torque tube l5 in alignment with the head 8. The tube I5 is .welded at It to a smaller resilient torque tube l'l telescoped therewithin and carrying on its free end a flange l8. Bolted to the flange II is a sleeve I! having splined therein a removable jaw similar to the starter Jaw 2 and having teeth adapted for engagement thereby. The Jaw 20 is removably secured in the sleeve I! by means of a central bolt 2| whereby diflerent laws may b substituted to' accommodate different types of starters.

The sleeve I5 is supported against lateral movement by means of a ball bearing assembly 22 carried by a part3! the base 5 directly behind the head I in the manner shown in Figure 2.

The arrangement is such that when a starter ismounted on the head I the starter Jaw 2 may be extended into positive engagement with the eo-mating jaw 20 splined in the sleeve It. When the starter torque is applied to the Jaw 20, the sleeve I9 is free for rotation in the bearing assembly 22 to the extent of the combined torsional deflection occurring in the torque tubes I5 and. II. For recording purposes the torsional deflection of the sleeve I9 is magnified by a radial arm 23 bolted between the flange l5 and the sleeve l9 and carrying a pencil 24 at its lower extremity. Movements of th arm 23 are guided and damped by a pair oi plates 25 and 25 bearing against opposlte sides thereoi and supported on bosses 21 and 28 on the base portion 5.

The plate 25 carries a fixed reference pencil 25 in line with the no load position 01' the movable pencil 24, the pencils 24 and 28 being thus arranged ior making tracks or curves upon apaper tape 30 as the latter moves over a platen or platform 3|. A plurality of pressure rollers 52 are retained by a spring clip 33 secured by screws 54 to hold the paper 30 flat against the platen 3| beneath the pencils. The numeral 35 designates a paper roll carried in a paper holder 38, and the numeral 31 designates a reduction gear paper drive powered by an electric motor 35.

A plurality of switches are mounted exteriorly on the base 5 for energizing the starter motor, the starter jaw meshing solenoid, and the paper driving motor 35 for the coordination of these functions in proper sequence.

Referring now to Figures 2, 5 and 6, cam means will be ribed for exerting a clamping action on the clamping arms ID to hold the starter I securely against the head 5 in th same manner that th starter would be supported upon an engine mounting pad. The arms II are provided with elongated slots for loose pivotal movement about pins 45 carried by the base 5 whereby the arms may have both pivotal and longitudinal clamping movements subject to the biasing action or spring actuated balls 41 abutting pins 48 on the bas 5. A pair or operating levers 50 carried by vertical shafts 5| iournaled in the base 5 have cam portions 52 engageable with shoulders on the arms III to produce longitudinal clamping movement in the arms. Pins 54 on the operating levers 55 are connected by an over-center spring 55 adapted to maintain these levers either in the clamping position shown in Figure 5 or in the release position shown in Figur 6. In the position oi Figure 5 the inward motion or 4 the levers 50 is stopped by the operation oi. the clamping mechanism Just described, and in the position of Figure 6 the motion of the levers II under spring tension isstopped by the engagement of pins 55 on shafts 5| with abutments 51 on the base 6.

When the levers 50 are swung outwardly to the position shown in Figure 6, the earns 52 are rotated clear'oi the shoulders 53 permitting the arms Ill pivotaland longitudinal movement as shown. Shoulders 58 of arms l0 ride on cams 52 to maintain arms It in their outward position of Figures 6 and locked against inadvertent movement inwardly to be in their starter base clamping positions of Figures 2 and 5. To clamp the clamping arms ill they are first swung inwardly to grasp the starter base flange and then the levers 50 ar rotated inwardly toward the position shown in Figure 5. This inward motion of the levers 50 rotates the earns 52 in such a man ner that the rising cam surfaces engage the shoulders 55 to move the arms I0 longitudinally into powerful engagement with the starter base flange. The slope of the cam surfaces is such that the spring 55 is adequate to maintain this clamping action as shown in Figures 2 and 5 once this position of the parts has been manually produced. The dowels ll furnish guiding support and prevent rotation of the starter on the head 5 under torque reaction.

The above described clamping mechanism is the invention of Philip F. Scoiield being claimed in application Serial No. 542,700, flled June 29, 1944, entitled "Starter test stand",and assigned to the assignee of the present invention.

As far as the starter is concerned, the operation of the present torque recorder simulates an attempted starting operation on a frozen" engine. When the rotating start-cit" Jaw 2 is advanced into engagement with the locked Jaw 25 the energy of the flywheel is dissipated in the starter clutch causing a torsional deflection of the torque tubes and a corresponding movement of the recording arm 23 to move the pencil 24 transversely across the paper tape 35. In such a simulated starting operation with the paper tape 50 travelling beneath the pencils 24 and II. a continuous curve will be traced by the pencil '14 and the torque indicated at any point may be readily determined by measuring the distance between this curve and the straight line traced by the i'ixed pencil 29. Thus it is seen that the traced curve is independent of the exact alignment or position of the edge oi the paper in its travel over the platen 3|, the only requisite being that the paper he made to travel at a uniform speed and maintain itself in such a position that both pencil tracks remain on the paper, the track from pencil 28 serving as a reference base line throughout the length or the curve.

The outstanding characteristic of the present testing device is its frequency respons whereby it faithfully follows and records extremely high frequency torque pulsations which have heretofore escaped detection in conventional testers. Known devices previously employed in testing and calibrating clutch torque and the like have been effective only to indicate the average values and have not been operative to portray a graphic picture oi clutch action in terms of instantaneous torque values plotted against time. With the present device the paper speed may be adjusted by known means so that each pulsation may be measured separately in the determination oi viand amplitudes from a low bration frequency mounting for well adapted for static testing, such as in frequency chatter to a high pitched vibration. This characteristic is extremely useful and necessary inasmuch as a mere average torque indication does not reveal the frictional variations which may be occurring rapidly bewteen the clutch discs. It is desired to know whether the torque is being exerted by a smooth slipping action or whether the discs alternately bind and slip.

Severe cases of chattering or vibration may be detected by the ear but it has been found in using the present device that many clutchespresumed to be good by a mechanic's ear test have produced very unsatisfactory graphic records. clutch is a piece of mechanism which is designed to operate only intermittently and testing procedure which attempts. to parallel service conditions to determine such factors, for instance, as the ultimate life of the clutch, require long periods of time to produce failure. By coordinating. a study of torque and vibration characteristics with destruction tests on sample clutches, information is obtained which is of great value in predicting the life and performance of clutches to be put in service.

The previously mentioned damping action of the plates 25 and 26 on the arm 23 is such as to make the arm faithfully follow the movements of the sleeve l9 without rendering the device unresponsive to high vibration frequencies. The stiffness of the tubes l and I1 is such that the natural frequency of the system is far beyond the range of vibration frequencies encountered in starter clutches whereby the system is sensi tively responsive to any amplitude or frequency of clutch vibration'encountered. v

If desired, the outer tube l5 may be made relatively stiff and rigid so that practically the total deflection-occurs in the inner tube I1. Regardless of which tube experiences the greater angular deflection, the telescoping arrangement preserves the advantage of a compact and unitary both the starter and the recording mechanism in a common housing at one end of the torque tube assembly.

It is understood that the terms stylus, pencil and marking means are used in a broad sense to include any type of scribing device capable of drawing a curve on a moving tape and the like. The type of stylus at present preferred comprises a lead or lead pencil holder having a light spring to press the marking material firmly against the moving paper, it having been found that ink recording mechanisms were unsatisfactory for high vibration frequencies. By accurately making the lead holder and carefully adjusting the spring pressure, a pencil marker will satisfactorily record extremely high frequency vibrations.

Although the dynamic recording of instantaneous values has been emphasized as the outstanding characteristic and advantage oi the device, it is to be understood that it is equally locked rotor motor test where the moving parts are all at rest, and this double utility constitutes a still further advantage of the present arrangement.

In other words, such a locked rotor motor test could also be made if the jaws 2 and 20 were ini ,tially engaged and at rest while the arms it are clamping the starter base instead of the laws being separated as shown in Figure 2 and only engaged after the starter operates to throw jaw 2 out into mesh with jaw 20. Also, static loading may be utilized for purposes of calibration by A starter providing a weight on a lever arm interlocked with the Jaw member 20.

Various changes may be made in the construction and arrangement and all such modifications are included in the invention, the same being limited only by the scope of the appended claims.

We claim:

i. A clutch .torque recorder comprising a resilient member'having one end fixed and the other 10 end rotatably free and adapted to have a variable torque applied thereto, a radial arm carried by said member, a pair of friction plates engaging opposite sides of said arm to damp out movements thereof, a stylus carried by one of said plates. and a stylus carried by said arm.

2. A clutch torque recorder comprising a base housing, means on said housing for mounting a clutch mechanism to be tested, a, torsionally resilient memberhaving one end fixed in said housing and having the other end rotatably free and adapted for engagement by element in said mechanism, a radial arm carried by said member and disposed within said housing, a stylus carried by said arm, and a paper moving mechanism in said housing associated with said stylus.

3. A clutch torque. recorder comprising a housing, a head on said housing adapted to receive a clutch mechanism to be tested, cam means on said housing for clamping a on said head, a resilient member having one end fixed in said housing and havingthe other end rotatably free and adapted for engagement by a torque delivering element in said mechanism, a radial arm carried by said member within said housing, and a stylus carried by said arm.

4. A dynamic clutch torque recorder comprising a housing, a head on said housing adapted to receive an for clampin said starter on said head, a resilient tube fixedly mounted at one end to said housing and having a free end mounted in a. bearing in said housing, a jaw secured to said free end so as to be engageable by a jaw in said starter, a radial 4 arm rotatable by said jaw, and a stylus carried by said arm.

5. A dynamic clutch torque recorder comprising a housing, a head on said housing adapted to receive an inertia starter and the like, means for clamping said starter on said head, a resilient tube fixedly supported at one end by said housing, a second resilient tube within said first tube and fixed thereto at the other end thereof, a hearing in said housing, a jaw secured to the free end of said second tube and mounted in said bearing for engagement by a law in said starter, a

radial arm movable by said Jaw, and a stylus carried by said arm.

6. In a dynamic clutch torque recorder, a houring, a head on said housing adapted to receive an inertia starter and the like, means for clamping said starter on said head, a bearing in said housing, a torsionally, resilient sleeve having one end fixedly mounted to said housing andthe other end rotatably mounted .in said bearing, a jaw re- '7. In a dynamic clutch torque recorder, a hous min a head on said housing adapted to receive an inertia starter and the like having an extendable jaw, means for clamping said starter on said head, a bearing in said housing, a torsionally rosilient sleeve having on end fixedly mounted to 16 said housing and the other end rotatably mounta torque delivering clutch mechanism inertia starter and the like, means movably secured in said sleev for engagement manipulatabie means for binding said arms into iirm clamping enzacement with a base flange on said starter to hold said starter rigidly on said head, a resilient tube fixedly mounted at one end on said housing, a second resilient tube within said first tube and having one end fixedly united with the free end thereof, a flange On the free end or said second tube, a i'ianged sleeve secured to said flange, a bearin in said housing carrying said sleeve, a jaw splined in said sieeve for engagement with said extendable starter Jaw, a radial arm carried by said flanges, a stylus carried by said arm, damping means ior said arm. a fixed stylus carried by said damping means, and means for moving a paper tape in operative relation with said styluses.

LYSLE D. CAHILL. JOSEPH J. NEFF, FORREST A. FRAMPTON. 

